1. Field of the Invention
The present invention pertains to the field of filling systems for fluid tanks of motor vehicles, and more particularly systems for filling a tank with urea for use in vehicular emission control systems.
2. Description of the Related Art
As is generally known, motor vehicles require several different fluids for their operation, which may include fuel, cooling fluids, and urea. A general concern in the design of containers for these fluids is the need to prevent inadvertent filling of a container with a different fluid than the one for which it is intended. Such an erroneous fill-up can seriously damage the system that receives the wrong fluid, and, in the case of fluids for emission control systems such as urea-based NOx decomposition systems, it may cause non-compliance to the emission standards which the system in question is intended to ensure meeting.
Another concern in the design of filling systems for containers of vehicle fluids is the need to remove any vapor or gas present in the container during the process of filling the container with the desired fluid.
With respect to urea tanks, used for example in vehicles adapted to remove the NOx from the engine's exhaust fumes, the above concerns are addressed by two known systems.
The “Elaflex” system dispenses a urea solution from a nozzle spout with a diameter of approximately 19 mm and a compatibly sized socket mounted on the tank to receive the nozzle. The diameter of the socket is chosen in such a way that use of a standardized diesel or gasoline nozzle is physically prevented. Furthermore, in an approach similar to the one disclosed in U.S. Pat. No. 5,562,133 to Mitchell, the Elaflex socket contains a magnet of annular shape that cooperates with a magnetically actuated valve in the nozzle to authorize its operation. A disadvantage of the “Elaflex” system is that filling can only take place at a compatible filling station.
The “Kruse” system dispenses a urea solution from a bottle, which is screwed in an inverted position onto a threaded socket mounted on the tank. To allow the fluid to flow out of the “Kruse” bottle and into the tank, the bottle must be pressed down in order to switch the valve mounted on the bottle's protruding axis into an open position. The system will then on the one hand provide a flow of urea solution from the bottle into the tank, and on the other hand provide a corresponding flow of air and vapor from the tank to the bottle. A disadvantage of the “Kruse” system is that the fluid is dispensed rather slowly, compared to the “Elaflex” system.
Whereas each of the systems described above has its own advantages and disadvantages, some of which may be more pertinent to particular users than to others, it is particularly inconvenient and disadvantageous that vehicle designers have to choose compatibility with a single system, thereby precluding the use of the other system by the end user.